Before You File a Bug Report Please Confirm You Have Done The Following...

• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.
• I have searched for related issues and found none that matched my issue.
• I have read the FAQ and my problem is not listed.

Playground Link

https://typescript-eslint.io/play#ts=5.9.2&fileType=.tsx&code=CYUwxgNghgTiAEYD2A7AzgF3gIyUiAXDnhCFCgNwBQy6WA3vFPALzwDkoAZlAK4QZ28AL6ti%2BeAH54jKEXYAJEBAhIhoovWEUgA&eslintrc=N4KABGBEBOCuA2BTAzpAXGUEKQAIBcBPABxQGNoBLY-AWhXkoDt8B6Jge1tmUSWWS0AJogBmAQwR1xAygHMmAW0Qt0URNGgdokcGAC%2BIfUA&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eAcgK6qoDCAFutAGsylBm3TgwAXxCSgA&tokens=false

Repro Code

declare const bool: boolean;
const { a = 'default' } = bool ? { a: 'Hello' } : {};

ESLint Config

{
  "rules": {
    "@typescript-eslint/no-useless-default-assignment": "error"
  }
}

tsconfig

{
  "compilerOptions": {
    "strictNullChecks": true
  }
}

Expected Result

Don't report = 'default'

Actual Result

Default value is useless because the property is not optional

Additional Info

Originally reported by @jimmy-zhening-luo in #11847 (comment).